Although, there are many (new) languages for the JVM, Scala
(http://www.scala-lang.org/) is one of or probably the most popular one (>2000
downloads per month). However, to be productive one is forced to work with
eclipse since there is no netbeans module yet.
Not sure, but http://www.scalabeans.com/ might be going somewhere.
There's another one here
The contrib/scala.* project (http://wiki.netbeans.org/Scala), developed by Caoyuan Deng, is the most active and advanced
Scala support for NetBeans. Caoyuan, note the 56 votes on this issue (second most voted) - you have many fans! ;-)
I'm eager to use Scala on NetBeans too, thus it's also on my own top list :-)
To get better progress, I need the supports from Schlimann, GSF and coming Parsing APIs
This is in fact voted #1 on
by a good margin!
BTW if production-quality support is planned for a particular release, you can add the keyword PLAN if you want this to
appear in lists such as
(according to priority and target milestone).
There will be a beta release soon, with features:
syntax and semantic coloring, source file navigator, code folding, mark occurrences, go to declaration, instant rename,
indentation, formatting, pair matching, error annotations, smart code completion, project management, interactive
No sense tracking it here. See: http://java.net/projects/nbscala